1. Field of the Invention
The present invention relates to a recording material image capture device for capturing an image (taking an image) of a surface of a recording material, and to an image forming apparatus.
2. Description of the Related Art
An electrophotographic image forming apparatus such as a copying machine and a laser printer includes an image bearing member for bearing a latent image, a developing device for visualizing the latent image as a developer image by applying a developer to the image bearing member, a transfer unit for transferring the developer image, which is formed by the developing device, onto a recording material conveyed in a predetermined direction under predetermined transfer conditions, and a fixing device for fixing the developer image onto the recording material by heating and pressurizing, under predetermined fixing conditions, the recording material onto which the developer image is transferred by the transfer unit.
Conventionally, in such an image forming apparatus, the size and the type of the recording material are set by a user through a control panel or the like of the image forming apparatus. The image forming apparatus is controlled so that the transfer conditions (for example, the transfer bias voltage or the speed of conveying the recording material in transfer) or the fixing conditions (for example, the fixing temperature or the speed of conveying the recording material in fixing) are set in accordance with the settings.
In recent years, there has also been proposed an image forming apparatus which determines the type of the recording material using a sensor for determining the recording material in the image forming apparatus and controls to set the transfer conditions or the fixing conditions in accordance with the result of the determination.
For example, Japanese Patent Application Laid-Open No. 2010-266432 describes determination of the smoothness of a surface of a recording material with high accuracy by radiating light at a relatively small angle (about 10 to 15 degrees) with respect to the surface of the recording material to be detected, producing a shadow due to unevenness on the surface of the recording material, and capturing an image of the shadow.
Japanese Patent No. 4,447,975 describes suppression of flaps of a recording material by providing an urging plate opposed to a detecting portion of an optical sensor and pressing, with the urging plate, the recording material against the detecting portion of the optical sensor when the recording material to be detected is conveyed.
In Japanese Patent Application Laid-Open No. 2010-266432, light is radiated at a relatively small angle (about 10 to 15 degrees) with respect to the surface of the recording material and a shadow is produced due to unevenness on the surface of the recording material. When an image of the shadow is captured, during the period in which the recording material to be detected is conveyed, the vertical positional variations (flaps) of the recording material are generated to the extent higher than assumed. In such a case, if the property of the surface of the recording material cannot be optically captured with high accuracy, the accuracy of determining the recording material is reduced.
Therefore, as in Japanese Patent No. 4,447,975, the flaps may be suppressed by providing a light transmissive member which passes through light to the side of a sensor for capturing an image of the surface of the recording material and pressing, with the urging plate, the recording material against the light transmissive member. However, depending on the pressing force of the urging plate and the type of the recording material, the light transmissive member is repeatedly rubbed against the conveyed recording material and thus is damaged.
In this case, the sensor for capturing an image of the surface of the recording material receives light which passes through the damaged light transmissive member, and irregular reflection components are increased by the damage. Therefore, there is a problem in that an image of a shadow on the surface of the recording material cannot be captured with high accuracy.